If you're not in a rush to buy something, it pays to wait for a lower price. The Tracktor indexes present and historic Amazon prices to tell you when the best time to buy is.

At The Tracktor, you plug in a product name, ASIN, or the full product name and The Tracktor will pull up the current price, its last change—whether the price has risen or fallen—and offer you a chance to set an email alert for when the price is at or below your specified level.

If you're willing to hold off on your purchase, the email alert combined with the historical price chart—seen below—can save you the most money.

If you look at the price chart above for the game Dominion you'll see a price drop around Christmas—a common trend for many products, especially games. If you weren't in a hurry to buy you could set a reminder and know that a similar price drop would be coming as the holidays drew near.

The Tracktor is a free service that requires no registration for basic searches but does require a simple email-based registration if you want email price-drop alerts. Have a favorite service for tracking prices on Amazon or otherwise? Let's hear about it in the comments.